Field of the Invention
This invention relates to detergent tablets having a uniform composition and a broad solubility profile for use in dishwashing machines wherein part of the tablets dissolves during the prerinse cycle, and the major portion of the tablets dissolves during the mainwash cycle.
Dishwashing in dishwashing machines generally comprises a prerinse cycle, a main-wash cycle, one or more intermediate rinse cycles, a clear-rinse cycle and a drying cycle. This applies both to domestic and to institutional dishwashing.
Heretofore, it has been standard practice in domestic dishwashing machines, hereinafter referred to as DDWM, to store the detergent in a dispensing compartment which is generally situated in the door of the machine and which opens automatically at the beginning of the main-wash cycle. The previous prerinse cycle is completed solely with cold tap water flowing into the machine.
In institutional dishwashing machines, hereinafter referred to as IDWM, the preliminary clearing zone corresponds in principle to the prerinse cycle of a DDWM. In machine dishwashing in large kitchens the detergent fed into the main-wash zone is actually used by overflow in the so-called preliminary clearing zone for the supportive removal of adhering food remains. Although there are also IDWM in which the preliminary clearing zone is supplied solely with fresh water, a preliminary clearing zone supplied with detergent solution is more effective than a preliminary clearing zone supplied solely with fresh water.
The object of the present invention is to apply the action principle of the preliminary clearing zone of a IDWM to a DDWM. The addition of detergents to the actual prerinse cycle was regarded as one possibility. In tests carried out with standard DDWM detergents, the effect of this was that, in addition to the usual dispensing of the detergent through the dispensing compartment in the door, more of the detergent had to be introduced into the machine itself. However, it is a well-known problem that flow-deficient regions exist both at the bottom of the machine and in the liquor sump of the machine. As a result, the product can never be adequately dissolved and, on completion of the prerinse cycle, has to be pumped off virtually unused.
Scattering detergent into the cutlery basket via the cutlery placed therein is not advisable because irreversible damage can be caused to silver and fine steel.
It has now surprisingly been found that the disadvantages mentioned above do not arise where the detergent tablets according to the invention are used. The addition of one or more tablets may be effected for example, in an empty part of the cutlery basket or even elsewhere in the machine.